[bzoj1968][Ahoi2005]COMMON 约数研究

Posted 2020-09-11 FallDream

[bzoj1968][Ahoi2005]COMMON 约数研究

来自FallDream的博客，未经允许，请勿转载，谢谢。

---

n<=1000000

这个嘛  直接枚举因数就好啦。

#include<iostream>
#include<cstdio>
#define MN 1000000
#define ll long long
using namespace std;
inline int read()
{
    int x = 0 , f = 1; char ch = getchar();
    while(ch < \'0\' || ch > \'9\'){ if(ch == \'-\') f = -1;  ch = getchar();}
    while(ch >= \'0\' && ch <= \'9\'){x = x * 10 + ch - \'0\';ch = getchar();}
    return x * f;
}

int n;
ll ans=0;

int main()
{
    n=read();
    for(int i=1;i<=n;i++)
        ans+=n/i;
    printf("%lld\\n",ans);
    return 0;
}